The rapid proliferation of unmanned aerial systems (UAS, also unmanned aerial vehicles (UAV)) necessitates systems and methods suitable for the integration of such systems into shared airspace. One of the most critical challenges associated with the integration of small UAS into shared airspace is effective traffic management. The size and altitude of many UAS are such that traditional air traffic control systems such as surveillance radar are inappropriate. Additionally, requiring continuous human monitoring of every UAS is untenable, especially as the number of UAS increases. Automatic Dependent Surveillance-Broadcast (ADS-B) is an exemplary alternative next-generation surveillance technology in which ADS-B compliant vehicles determine their positions via high-integrity satellite navigation (e.g. GPS) and broadcast their positions, along with other relevant data, such that other vehicles and/or ground stations can receive the signals. In this way, the ADS-B system can work in tandem with other aircraft management systems such as collision avoidance systems (e.g., Traffic Collision and Avoidance Systems, or TCAS). In the United States, all aircraft operating in airspace classes A, B, C, and E will be required to be equipped with equipment to transmit ADS-B information in the form of ADS-B Out signals.
It is noted that surveillance technology such as ADS-B is not itself sufficient to integrate UAS into shared airspace. The particular performance metrics of a UAS (such as Size, Weight, and Power (SWaP) metrics) along with the lift-to-drag (L/D) ratio critically impact the mission restrictions of a UAS. In general, communications systems (including antennas, power supplies, and associated circuitry) negatively impact the performance metrics of a UAS. As such, the greater the transmission power required for a communication system (e.g. ADS-B Out), the greater the power requirements and thus the lower the performance metrics. Accordingly, there is a need to develop guidance systems and methods to balance traffic control requirements with UAS performance metrics.
It is further noted that the spectral capacity of any communications network is limited, and that efficient use of spectral capacity becomes increasingly important as the number of devices on the network increases. It is expected that continued advances in UAS technology will continually increase the number of UAS systems in operation, and thus continually increase pressure on communications networks (e.g. ADS-B) associated with guidance and traffic management of both manned and unmanned systems. As a consequence, in order to optimize spectral capacity and reduce interference, it may not be desirable for every aircraft within a shared airspace to maintain constant bi-directional communication. Rather, in some applications, it may be desirable to assign aircraft into segregated airspaces, which may be defined by geographical location (e.g. near an airport) or elevation. In this way, aircraft are assigned to an airspace category according to the mission and/or technological capabilities of the aircraft (including, but not limited to, communications capability or degree of maneuverability). In other applications, it may be desirable to employ traffic-control and/or sense-and-avoid (SAA) systems such that multiple types or classes of aircraft share a common airspace. Accordingly, there is a further need to develop UAS guidance systems and methods that minimize the impact on the spectral load of the communications network in which the UAS operate.